TECHNIQUES FOR HOST TO HOST TRANSFER OF SEQUENTIAL MEDIA AND USE OF PERSISTENT RESERVATION TO PROTECT MEDIA DURING HOST TO HOST TRANSFER

• US 20080244032A1
• Filed: 03/30/2007
• Published: 10/02/2008
• Est. Priority Date: 03/30/2007
• Status: Active Grant

• Current Assignee: Veritas Technologies, LLC (Whitehouse Group Ltd.)
• Original Assignee: Symantec Corporation (NortonLifeLock Inc.)
• Inventors: GILSON, RAYMOND WESLEY, PARK, ADONIJAH
• Granted Patent: US 8,060,642 B2
• Time in Patent Office: Days
• US Class Current: 709/216
• CPC Class Codes: G06F 3/061 Improving I/O performance
• CPC Class Codes: G06F 3/0616 in relation to life time, e.g. increasing Mean Time Between Failures [MTBF]
• CPC Class Codes: G06F 3/0619 in relation to data integrity, e.g. data losses, bit errors
• CPC Class Codes: G06F 3/0631 by allocating resources to storage systems
• CPC Class Codes: G06F 3/0635 by changing the path, e.g. traffic rerouting, path reconfiguration
• CPC Class Codes: G06F 3/0682 Tape device
• CPC Class Codes: G06F 3/0686 Libraries, e.g. tape libraries, jukebox
• CPC Class Codes: H04L 67/1097 for distributed storage of data in networks, e.g. transport arrangements for network file system [NFS], storage area networks [SAN] or network attached storage [NAS]

Abstract

Techniques for host to host transfer of media and the use of persistent reservation to protect media during host to host transfer is disclosed. Exemplary embodiments may be realized as methods and systems for transferring a sequential media loaded in a drive from a first host to a second host without physically unloading the media. The first host may have a persistent reservation or non-persistent reservation of the drive. Likewise, the second host may have a persistent reservation or non-persistent reservation of the drive. Logical unload, logical load and preemption commands are utilized as is error recovery from a failed reservation.

Claims

1. A method operable in a controlling server for transferring a media loaded in a drive from a first host to a second host, wherein the first host comprises a non-persistent reservation of the drive;

the method comprising;

sending a logical unload command instructing the first host to logically unload the media and release the non-persistent reservation;

determining if the second host will establish a non-persistent reservation or persistent reservation of the drive; and

sending a logical load command instructing the second host to logically load the media.

2. The method of claim 1, wherein if it is determined that the second host will establish a non-persistent reservation, the logical load command further comprises an instruction to establish the non-persistent reservation of the drive.

3. The method of claim 1, wherein if it is determined that the second host will establish a persistent reservation with the drive, the method further comprises generating a key for use by the second host in establishing the persistent reservation.

4. The method of claim 3, the logical load command further comprises an instruction for the second host to establish the persistent reservation of the drive using the generated key.

5. The method of claim 4, wherein the key comprises an identifier of the drive and an identifier of the host.

6. The method of claim 5, wherein the keys further comprises an allocation index associated with the drive/media coupling.

7. The method of claim 1, wherein the media is transferred from the first host to a second host without physically unloading or loading the media.

8. The method of claim 1, wherein the persistent reservation comprises a SCSI persistent reservation.

9. The method of claim 1, wherein the media comprises sequential media.

10. The method of claim 9, wherein the sequential media comprises magnetic media.

11. At least one signal embodied in at least one carrier wave for transmitting a computer program of instructions configured to be readable by at least one processor for instructing the at least one processor to execute a computer process for performing the method as recited in claim 1.

12. At least one processor readable carrier for storing a computer program of instructions configured to be readable by at least one processor for instructing the at least one processor to execute a computer process for performing the method as recited in claim 1.

13. A method operable in a controlling server for transferring a sequential media loaded in a drive from a first host to a second host without physically unloading the media, wherein the first host has a persistent reservation of the drive;

the method comprising;

sending a logical unload command instructing the first host to logically unload the media and retain the persistent reservation;

determining if the second host will establish a non-persistent reservation or persistent reservation of the drive; and

sending a logical load command instructing the second host to logically load the media.

14. The method of claim 13, wherein if it is determined that the second host will establish a non-persistent reservation, instructing the first host to release the persistent reservation.

15. The method of claim 14, wherein the logical load command further comprises an instruction to the second host to establish the reservation of the drive.

16. The method of claim 13, wherein if it is determined that the second host will establish a persistent reservation, the method further comprises generating a key for use by the second host in establishing the persistent reservation.

17. The method of claim 16, further comprising, sending a preemption command to second host instructing the second host to preempt the persistent reservation of the first host, the preemption command comprising a key of the first host and the generated key of the second host.

18. The method of claim 17, wherein each of the key of the first host and the generated key of the second host comprises an identifier of the drive and an identifier of the host.

19. The method of claim 18, wherein each of the key of the first host and the generated key of the second host further comprises an allocation index associated with the drive/media coupling.

20. The method of claim 13, wherein the media is transferred from the first host to a second host without physically unloading or loading the media.

21. The method of claim 13, wherein the persistent reservation comprises a SCSI persistent reservation.

22. The method of claim 13, wherein the media comprises sequential media.

23. The method of claim 22, wherein the sequential media comprises magnetic media.

24. At least one signal embodied in at least one carrier wave for transmitting a computer program of instructions configured to be readable by at least one processor for instructing the at least one processor to execute a computer process for performing the method as recited in claim 13.

25. At least one processor readable carrier for storing a computer program of instructions configured to be readable by at least one processor for instructing the at least one processor to execute a computer process for performing the method as recited in claim 13.

26. A method operable in a controlling server for error recovery from a failed persistent reservation, the method comprising:

receiving an error message from the host comprising a key held by the drive for a persistent reservation;

determining if the key was generated by the controlling host; and

controlling the recovery of the drive if the key was generated by the controlling host.

27. The method of claim 26, wherein controlling the recovery of the drive comprises:

generating another key;

sending a command to the host or another host instructing the host or another host to preempt the reservation of the drive using the generated another key and to physically unload a media from the drive.

28. The method of claim 26, wherein the key comprises at least two of a drive identifier, host identifier or drive/media coupling allocation index identifier.

29. The method of claim 27, wherein determining if the key was generated by the controlling host, comprises:

determining if at least one portion of the key matches at least one of drive identifier, host identifier, or media allocation index identifier stored by the controlling host.

30. The method of claim 26, further comprising sending a preempt command instructing a host to preempt a persistent reservation of a drive.

31. At least one signal embodied in at least one carrier wave for transmitting a computer program of instructions configured to be readable by at least one processor for instructing the at least one processor to execute a computer process for performing the method as recited in claim 26.

32. At least one processor readable carrier for storing a computer program of instructions configured to be readable by at least one processor for instructing the at least one processor to execute a computer process for performing the method as recited in claim 26.

33. A system for transferring a media loaded in a drive from a first host to a second host, wherein the first host comprises a non-persistent reservation of the drive comprising:

means for sending a logical unload command instructing the first host to logically unload the media and release the non-persistent reservation;

means for determining if the second host will establish a non-persistent reservation or persistent reservation of the drive; and

means for sending a logical load command instructing the second host to logically load the media.

34. A system for transferring a media loaded in a drive from a first host to a second host, wherein the first host comprises a persistent reservation of the drive comprising:

means for sending a logical unload command instructing the first host to logically unload the media and retain the persistent reservation;

means for determining if the second host will establish a non-persistent reservation or persistent reservation of the drive; and

means for sending a logical load command instructing the second host to logically load the media.

35. A system for error recovery from a failed persistent reservation comprising:

means for sending a preempt command instructing a host to preempt a persistent reservation of a drive;

means for receiving an error message from the host comprising a key held by the drive for a persistent reservation;

means for determining if the key was generated by the controlling host; and

means for controlling the recovery of the drive if the key was generated by the controlling host.